Photochromic composition containing polyhalogenated hydrocarbon,spiropyran compound and zno or pb(ii) oxide and the use thereof

ABSTRACT

A PHOTOGRAPHIC PROCESS WHEREIN A VISIBLE IMAGE IS FORMED BY PRINT-OUT OR OPTICAL DEVELOPMENT IN A RECORDING MATERIAL COMPRISING IN INTIMATE ADMIXTURE A SPIROPYRAN COMPOUND, AN ULTRAVIOLET LIGHT-SENSITIVE COMPOUND CAPABLE OF PRODUCING ON EXPOSURE WITH ULTRAVIOLET LIGHT WITH THE SPIROPYRANE DYE SALT AND A SENSITIZING AGENT AN INORGANIC COMPOUND PRODUCING PHOTOELECTRONS UNDER THE INFLUENCE OF ACTIVATING ELECTROMAGNETIC RADIATION AND HAVING A BASIC OR AMPHOTERIC CHARACTER. PREFERRED RECORDING MATERIALS CONTAIN A SPIRODINAPHTHOPYRAN COMPOUNT, CARBON TETRABROMIDE AND-/OR IDOFORM AND A SENSITIZING AGENT PHOTOCONDUCTIVE ZINC OXIDE IN CONJUNCTION WITH A TRIARY STIBINE AS ANTIFOGGING AGENT.

PHOTOCHROMIC COMPOSITION CONTAINING POLYHALOGENATED HYDROCARBON, SPIRO- PYRAN COMPOUND AND ZnO OR Pb(lI) OXIDE AND THE USE THEREOF Urbain Leopold Laridon, Wilrijk, and Jozef Willy van den Houte, Grimbergen, Belgium, assignors to Agfa- Gevaert N.V., Mortsel, Belgium No Drawing. Filed Sept. 1, 1971, Ser. No. 177,122

Claims priority, application Great Britain, Sept. 1, 1970,

Int. Cl. GllSc 1/52. 5/24 US. Cl. 96-48 R 21 Claims ABSTRACT OF THE DISCLOSURE This invention relates to photographic recording and reproduction of information and to materials suited therefor.

The use of particular spiropyrans in the manufacture of photographic recording materials is known, e.g. from the United States patent specification 2,953,454 of LB. Berman-Nat. Cash Reg, issued Sept. 20, 1960. The spiropyrans described therein are characterized as being reversibly transformable into a colored form by activating electromagnetic energy.

In many applications such reversible transformation is not desirable and therefore efforts have been made to obtain a print-out color image the color of which does not fade by keeping it in the dark or by a further irradiation with electromagnetic radiation dilfering in wavelength from the radiation originally applied.

In the German patent specification 1,274,655 a recording material has been described by means of which stable print-out dyestulf images can be obtained by using spiropyrans in admixture with a compound that activated with electromagnetic radiation can yield photolytically formed free radicals.

The starting substances for these radicals are preferably halogenated organic compounds.

The recording materials described in the latter Patent Specification need rather long exposure times with the conventional ultraviolet light sources.

It is an object of the present invention to provide a method for increasing the photosensitivity of recording materials which contain a photosensitive compound that by information-wise exposure to activating electromagnetic radiation yields a dyestufi image by reaction with a spiropyran compound.

It is another object of the present invention to provide a method for making visible or intensifying a latent image or barely visible image produced with said spiropyran and photosensitive compound. Said method is called hereinafter optical developmen for it operates with an overall exposure in the wavelength range of electromagnetic radiation absorbed by dyestulf traces formed in the image-wise exposure.

United States Patent 0 3,810,763 Patented May 14, 1974 It is a further object of the present invention to provide photographic materials suited for use in said methods.

It has now been found that the photosensitivity for forming a directly visible image or optical development sensitivity of a recording material containing in intimate admixture:

( l) at least one spiropyran compound, and

(2) at least one ultraviolet light-sensitive compound capable of producing on exposure with ultraviolet light with said spiropyran compound a dyestulf salt is increased by applying in working relationship with said mixture an inorganic compound producing photoelectrons under the influence of activating electromagnetic radiation and having a basic or amphoteric character.

Preferred inorganic compounds for that purpose are photoconductive zinc oxide and lead(II)monoxide.

Spiropyran compounds suited for photographic image formation according to the present invention are spiropyrans containing at least one pyran ring having in the orthoand meta-position to the oxygen atom a condensed benzo, naphtho or other higher aromatic polycyclic condensed ring system including these condensed rings or ring systems in substituted state, e.g. an anthraceno or a phenanthreno ring system, e.g. as present in a spirodibenzopyran, a spirodinaphthopyran, a spirobenzonaphthopyran, a 1,3,3-trimethylindolinobenzospiropyran, a 1,3,3-trimethylindolinonaphthospiropyran or such spiropyrans containing condensed aromatic nuclei of the anthracene or phenanthrene type.

In said spiropyrans the pyran rings, the condensed benzo, the condensed higher aromatic rings as well as the 1,3,3-trimethylindolino ring may be substituted.

Suitable substituents therefore are, e.g. hydrocarbon groups such as alkyl groups, e.g. lower alkyl groups such as methyl, substituted alkyl groups, e.g. halogen, or phenyl substituted alkyl groups, alkylene ester groups, e.g. a CH COOC H group, alkylene carboxyl groups, e.g. a CH -COOH group, carbonamide groups or substituted carbonamide groups, e.g. a

group, halogen, nitro, hydroxy, alkoxy, aryloxy or a substituent linking the carbon atoms in 3,3-position in the spiropyran system together, e.g. a (CH ),,-chain wherein n is 2 or 3.

General formulae covering particularly suited spiropyrans are the following:

wherein:

R, R R',, R R'g, R and R' represent hydrogen, an aliphatic group including a substituted aliphatic group, e.g. a (C -C alkyl group including such an alkyl group in substituted form, more particularly a methyl, ethyl, propyl, amyl or hexadecyl group or halogen substituted alkyl group, halogen, nitro, hydroxy, an alkoxy or aryloxy group, a phenyl group or a substituted phenyl group, piperidyl, an alkylene ester group, e.g. a CH OOOC I-I group, an alkylene carboxyl group, e.g. a CH COOH group, a carbonamide group or a substituted carbonamide, group e.g. a

group, or R and R; together represent a -(CH,),,- chain wherein n=2, or 3 to link the carbon atoms in the 3 and 3' positions together.

Suited spiropyran compounds and their preparations are described in the published German patent applications 1,274,655 filed Dec. 15, 1965 by Telefunken Patentverwertungs G.m.b.H., 1,269,665, 1,286,110, 1,286,111 and 1,286,112 all filed Sept. 30, 1966 by Telefunken Patentverwertungs G.m.b.H., and W. Dilthey, Berres, Holterkoff, Wiibken, J.'PrCh. [2] 114, 187 (1926), by C. F. Kolesch and W. R. Workman in I.A.C.S. 74 6288 (1952) and in J.Chem.Soc. (1934), 1567571 by I. M. Heilbron and G. F. Howard.

Preferred spiropyran compounds are spirodinaphthopyrans and spirobenzonaphthopyrans including such compounds wherein the naphthoand/or benzo ring(s) is (are) substituted.

An illustrative list of particularly useful spiropyran compounds is given in the following Table 1.

TABLE 1 Meltin olnt Spiropyran compound 8 TABLE 1--Cont1nugd Spiropyran compound V V V 13.: OCH: OCH: 260

Spiropyran Compound "(C IM-C I QF I? TABLE 1Cont inued Melting golnt Spiropyran compound C.) 29 n X: 160

(CHm-GH:

OCH;

Hn m

TABLE 1--C0ntinued Melting point Spiropymn compound C.)

Hav

PREPARATION 1 Preparation of 3-methyldi-fi-naphthospiropyran In order to illustrate in more details the preparation (compound 2 of Table of the diarylo spiro-pyran compounds and the indolino- 70 In a 2 hter three-necked flask, fitted wrth a reflux conarylospimpyran compounds the f llqwi preparation denser and a gas mlet tube reachmg nearly the bottom receipes are given; of the flask are introduced:

Ethanol lliter Butanone 22 ml. (0.25 mole) 7 5 Z-hydroxy-l-naphthaldehyde 86 g. (0.5 mole) The flask is shaked until partial dissolution of the ingredients. Dry hydrogen chloride gas is introduced at a rate which allows complete absorption and the start of ethanol reflux. Thereupon the already strongly blue colored mixture is cooled down in a mixture of ice and sodium chloride and the introduction of hydrogen chloride gas continued until saturation. In the reaction mixture green crystals of pyrylium salt are formed and the crystallization allowed to proceed overnight in a refrigerator.

The formed pyrylium salt is separated by suction, is washed with ethanol and thereupon brought into suspension in 300 ml. of ethanol.

While stirring a by weight aqueous solution of ammonium hydroxide is added until the mixture is definitely alkaline. During that operation the mixture becomes colorless.

The obtained crystalline product is separated by suction, washed with water and dried.

Finally the spiropyran compound is recrystallized from 600 ml. of benzene and again separated and dried ulnder reduced pressure at 50-60 C. Yield: 45 g. Melting point: 204 C.

PREPARATION 2 Preparation of 1,3,3-trimethylindolinobenzopyrylospiran (compound 22 of Table 2) In a 100 ml. flask fitted with a reflux condenser are introduced the following ingredients:

Salicylaldehyde 3.7 g. (0.03 mole) 1,3,3 trimethyl 2 methylene indolamine 5.1 g. (0.03 mole) Ethanol 90 ml.

The solution is boiled under reflux for a period of 2 hours. Thereupon the mixture is cooled down and filtered.

To the filtrate water is added for separation of a solid product. The solid is separated by suction, washed with water and dried under vacuum conditions.

The spiran compound is recrystallized from ml. of hexane.

Yield: 5 g. Melting point: 93-94" C.

The compound capable of producing a dye salt with a spiropyran on exposure to activating electromagnetic radiation is for use according to the present invention preferably an organic polyhalogen compound of which a halogen containing radical C8111 be photolytically separated. Compounds possessing that property are within the scope of the following general formula:

wherein: each of A, B, X and Y are halogen atoms of the group of chlorine, bromine or iodine, or wherein one of said radicals A, B, X or Y represents an alkyl group, including a substituted alkyl group, e.g., a halogen substituted alkyl radical, a hydroxyalkyl radical or an aralkyl radical, e.g., a benzyl radical, an aryl group, a substituted aryl group or an aroyl group and the other radicals chlorine, bromine or iodine, or wherein at least two of said radicals A, B, X or Y represent an aromatic acyl group, e.g., a benzoyl group and the other radicals chlorine, bromine or iodine.

Suitable representatives falling within the scope of that general formula are organic halides such as carbon tetrabromide, bromoform, iodoform, hexachloroethane, hexahexabromoethane, pentabromoet-hane, 1,1,2,2-tetrabromoethane, 11,,a-tribromoacetophenone and tribromoethanol.

The spiropyran compound(s) are preferably used in admixture with a 5- to -fold amount by weight of photosensitive organic halogen compound such as carbon tetrabromide. This ratio is, however, not limitative since useful results can be obtained with, e.g., the spiropyran and photosensitive polyhalogen compound in a ratio by weight in the range of 1:1 to 1:50.

wherein:

Z represents a sulphur atom or a single bond,

A represents a single bond or a divalent hydrocarbon group, e.g., a CH group,

R represents hydrogen or a lower alkyl radical, e.g., a

methyl radical,

R represents hydrogen or a lower alkyl radical, e.g., a

methyl or an ethyl radical,

Q and Q each represent a hydrogen atom or together the necessary atoms to close an adjacent carbocyclic ring or ring system including such ring or ring system in substituted form, preferably an aromatic ring (e.g., a benzene ring) including a substituted aromatic ring, e.g., a halogen substituted (chlorine, bromine or iodine substituted) benzene ring,

Q and Q each represent a hydrogen atom or together the necessary atoms to close an adjacent carbocyclic nucleus or ring system including such a ring or ring system in substituted form, preferably an aromatic ring (e.g. a benzene ring) including a substituted aromatic ring, e.g. a halogen substituted (chlorine, bromine or iodine substituted) benzene ring, and

n represents 1 or 2.

The N-vinyl polymers and copolymers can be prepared by application of one of the various known polymerization procedures, e.g., by pearlor emulsion polymerization or by polymerization in solution, whereby the initiation of the polymerization can occur by free radicals, by ion formation, or by radiation, e.g., with actinic light. It is to be noted that the polymerization degree is not critical and can vary between wide limits. As far as the copolymers are concerned, it is further to be noted that the content of groups corresponding to the general formula given hereinbefore is not critical and, as shown further-on in the table of copolymers containing N-vinylcarbazole units, can vary between wide limits, say, e.g. between 20 and 95%, taking into account the properties of the compounds used in the preparation of the copolymers and the required sensitizing and/or mechanical properties. In general, the best results are attained with copolymers having a content of vinylcarbazole units between 40 and The preparation of suitable poly-N-vinylcarbazoles is described, e.g. in the German patent specifications 931,- 731 filed Mar. 4, 1953, 936,421 filed Feb. 20, 1953, 1,097,- 680 filed Oct. 15, 1959 all three by B.A.S.F., and 1,158,- 367 filed July 18, 1962 by Gevaert Photo-Producten N.V., and the US. Pat. 2,072,465 of W. Reppe, E. Keyssner and E. Dorrer, issued Mar. 2, 1937. The preparation of poly- N-vinyl-pyrrole proceeds analogously.

The preparation of suitable N-vinylcarbazole copolymers is described in the United Kingdom patent specification 964,875 filed Apr. 21, 1960 by Gevaert Photo-Producten N.V.' which specificationalso contains a preparation receipt for poly(N-allyl carbazole) (R =CH and R ==H) and for poly(N-propenyl carbazole) (R =H, R =H, A=--CH The poly-N-vinyl indoles are described in the published German patent applications 1,906,831 filed Feb. 12, 1969 TABLE 2 Male percent of N-vinyl Copolymer carbazole ccpolymer of N-vinylcarbazole and vinylidene chloride 85. 4

-copolymer ct N-vinylearbazole and 3,3,5-trimethyi isononylether 93 -cnpolymer of N-vinylcarbazole and vinyl acetate 88. 6 -copolymer of N-vinylcarbazole and isopropenyl acetate. 94. 5 -copolymer of N-vinylearhazole and vinylstearate 37. 5 -co polymer ct N-vinylcarbazole and methylaerylate 67. 6 -copolymer of N -vinylcarbazole and ethylacrylate... 41 graft copolymer of N vinylcarbazole and ethylacryl 90. 3

acrylate -copclymer oi N-vinylcarbazole and n-butylacrylate -copolymer of N -vlnylcarbazole and 2-ethylhexylacrylate. -copoilymer oi N-vinylcarbazole and acryloxyethyldietliylam no -copolymer of N-vinyicarbazole and vinylcinnamate -copolymer of N-vinylcarbnzole and methylmethacrylate -copolymer of N-vinylearbazole and isobutylmethacrylate -copolymer of N-vinylcarbazole and laurylmethacrylate -copolymer of N-vinylcerbazole and mothylacryloxyethyl diethylamine -copolymer of N-vinylcarbazole and acrylonitrlle. -grait copolymer of N-vinylearbazole and but acetal o1 polyvinylalcohol -copolymer of N-vinylcarbazole (2 vinylphosphonate -copolymer of N-vinvlcarbazole and styrene -graft eopolymer oi N-vinylcarbazole and polystyrene- -copolymer of N-vinylcarbazole and vinylnaphthalene. -copolymer oi N-vinylcarbazole and anthracenMQJO)... -co polymer of N-vinyicarbazole and 2-vinylpyridine. -copolymer of N-vinylcarbazole and 4-vinylpyridine -copolymer of N-vinylcarbazole and N-vinylpyrrolidine -terpolymer f N-vinylearbazole, acrylonitrile and styrene. -grait copolymer 01a terpolymer of vinyl chloride, vinyl acetate and vinyl alcohol with N-vinylcarbazole -grait copolymer 0! a terpolymer of vinyl chloride, vinyl acetate and maleic anhydride with N-vinylcarbazole woo OW (B) organic compounds containing two radicals of different electron-affinity (the term radical includes group as well as atom) linked to each other through a conjugated system,

Useful sensitizing agents of class (B) are those having one of the following general Formulae I, II, III, IV, V

wherein:

D represents an electron-donating group, e.g. an alkyl (preferably C -C alkyl), cycloalkyl or aralkyl substituted amino or hydroxy group, preferably a monoalkyl amino group, a dialkylamino group or an alkoxy p,

Z represents a conjugated system, e.g. a polymethine chain or an azamethine chain including such chain that is substituted or makes part of a ring structure, e.g. a phenylene or a naphthylene ring,

R represents hydrogen, a hydrocarbon radical e.g. an alkyl, an aryl or a heterocyclic group preferably a methyl group or a phenyl group, or the necessary atoms to form a homocyclic or heterocyclic ring with an atom of the group Z,

Q represents the nonmetallic atoms necessary to complete a ring or ring system in which the group C=X through a conjugated system is linked to an electron-donating group as described for D,

X represents an electronegative atom or group, e.g. oxygen, =NR wherein R is hydrogen or an aromatic group, sulphur, selenium,

and other bivalent electron-attracting groups known in organic chemistry, prefer-ably however X represents oxygen or sulphur,

Q represents the nonmetallic atoms necessary to complete a ring or ring system wherein the group is linked through a conjugated system to an electronattracting group, e.g. a carbonyl group, a thiocarbonyl group, a sulfonyl group or a dicyanomethylene group, or represents the necessary atoms to form with the carbon atom of the group a heterocyclic ring having an electronegative character with respect to the group D, e.g. a benzoxazole ring, Y represents an electron-attracting group, e.g.

or the group wherein X has the same meaning as described above, Q represents a heterocyclic nucleus, containing an electron-donating group, e.g. a dialkylamino group that is linked through a conjugated system with the group wherein P and Q each represent an electron-attracting substituent, e.g. a cyano group or wherein P and Q together represent the necessary atoms to close a heterocyclic ring with electronegative character, e.g. as present in merocyanine dyes such as a ketomethylene ring of which a rhodanine nucleus is a particular example,

each of L and L represent a methine group or a substituted methine group, and

L represents a monovalent chemical bond, an a,p-ethylenically unsaturated bivalent group e.g. a

group or a plurality of said groups linked to each other,

or L L and L represent together a double bond linking the group to the group Preferred compounds falling within the scope of Formula III are described e.g. in the Belgian patent specification 747,849 filed Mar. 23, 1970 by Gevaert-Agfa N.V., corresponding with the US. Pat. application Ser. No. 22,376. Representatives thereof are, e.g.:

Preferred compounds falling within the scope of For- Preferred compounds falling within the scope of For- 10 male II are: a. c CH N- N\ mc A cm 15 4. EC CH; I

H10 5 CH:

5. H c i c N -N\ mc g N0 V 1L 6 11.0 v I cm 25 Preferred compou HgO iii: N

nds falling within the scope of Formula IV are styryl dye bases and styryl vinyl dye bases and compounds such as:

Ref. U.S. Pat. 2,793,792 0! J. B. Pllkington, issued May 28, 1957.

Rel. J. mm. Chem. 21, 151, p. 219

Rel. Ber. 89, p. 1748 (1956).

Ref. Ber. 89, p. 174.8 (1956).

Ref. U.S. Pat. 3,189,447 of Wilhelm Mengebauer, Martha Tomanek and 1185113 Behmenburg, issued June 15,

19 Preferred compounds falling within the scope of Formula VI are described in the United Kingdom patent specification 853,880 filed Dec. 16, 1957 by Kalle AG, e.g.:

HO H C N Preferred compounds falling within the scope of Formula V are merocyanines, e.g. those described in the United Kingdom patent specification 1,131,238 filed Nov. 16, 1965 by 'Eastman Kodak Co. Representatives thereof are, e.g.:

(C) organic compounds containing an aromatic nucleus or aromatic ring system in which two adjacent carbon atoms are common to said nucleus or ring system and to an adjacent ring which has no conjugated character and which at one end is linked to the aromatic nucleus or ring system through a carbon-carbon bond and at the other end is linked to said nucleus or ring system through an electron-donating group such as a secondary or tertiary amino group, said organic compounds include those having a said nucleus or ring system in substituted form.

' 20 Preferred compounds belonging to class (C) are described, e.g. in the Belgian patent specification 727,433 filed Jan. 27, 1969 by Gevaert-Agfa N.V. corresponding with the US. Pat. Appl. Ser. No. 793,881. Representatives thereof are e.g.:

n is a positive integer of at least 2, and R represents hydrogen or an alkyl group including a substituted alkyl group.

(D) organic nitrogen containing compounds having a thiol group or in their tautomeric form a thione group as represented in the following tautomeric structural parts:

HS( J=I I z s= 1'm Preferably used are heterocyclic compounds having the following tautomeric general formulae:

,1: ,x z: :=sn o=s wherein:

Preferred compounds falling within the scope of class (D) are, e.g.:

CHz-CH=CH3 1 H2 NH @LlH tetrahydro pyrimidine-Z-thiones, e.g.:

tetrahydroand dihydro-oxazine-Z-thiones and thiazine-2-thiones, e.g.:

H3 C-HC H2 1,3,4-dihydro thiadiazine-Z-thiones, e.g.:

thiourea compounds including substituted derivatives preferably N-phenyl thiourea compounds, e.g.:

l i m thioamides, e.g.:

22 to 50 parts by weight and the photosensitive reactant for forming the dyestufi salt, e.g. a photosentitive organic halogen compound such as carbon tetrabromide and/or iodoform in an amount of 10 to 250 parts by weight. These ratios are not critical and may be adapted to the circumstances and type of inorganic photoconductor.

The grain size of the inorganic sensitizing agent is in the range applied in electrophotographic materials. Vacuum deposited layers having no graininess are, however, not excluded on condition that a working contact between the sensitizer layer and said mixture of Com pounds 1 and 2 exists.

According to a preferred embodiment the photosensitive recording layer according to the present invention contains a film-forming binder. For that purpose preferably hydrophobic polymers are used that shield as much as possible the ingredients from a direct contact with the atmosphere and more especially from oxygen.

Particularly suitable binders for use in the present invention are hydrophobic polymers and copolymers, e.g. containing styrene, vinyl acetate, acrylonitrile, acrylic acid ester, methacrylic acid ester, N-vinylcarbazole or butadiene units, hydrophobic cellulose derivatives, phenoxy resins or polycondensates of the polyester type, e.g. polycarbonates.

These polymers can be used in a mixture-for improvement of the mechanical strength or adhering power of the recording layer to its support when no self-supporting layer is produced.

In order to diminish the rate of spontaneous thermal color formation over long periods of time as might be encountered during storage of the photographic material and processing of the photographic materials so-called antifoggants may be added to the photosensitive composition. Suitable antifoggants include triaryl compounds of Group V elements, e.g. triphenylstibine and sterically hindered phenols, e.g. 2,6-di-tert.butyl p-cresol and other reducing or atmospheric oxygen accepting agents. Triphenylstibine and analogous compounds for the purpose of the present invention are described in the United Kingdom patent specification 1,071,104 filed Aug. 14, 1964 by Horizons Inc.

A dry photographic coating containing the above mentioned ingredients may be formed by dissolving the binding agent(s) in a suitable inert solvent which acts as dispersing or dissolving medium for the other ingredients and which is removed from the coating composition by evaporation leaving a solid photographic recording layer on a properly chosen support. The supports may be of any kind encountered in silver halide photographic materials, e.g. paper and film supports.

In order to realize the highest sensitivity, it is desirable to coat the recording layers in the absence of oxygen or to keep them before the exposure in an oxygen-free environment.

The photosensitive organic polyhalogen compounds that in exposed state form with a spiropyran compound a dyestulf salt are normally only sensitive in a wavelength range between 400 and 250 nm.

Various sensitizing agents of the enumerated classes sensitize the recording composition in its inherent sensitivity range and it is assumed that they may also be considered as chemical sensitizing agents for they may chemi cally interact with photoradicals formed during the exposure.

A choice of a proper combination of sensitizing agents that are active for extending the sensitivity in the visible spectrum of the print-out recording composition used in the present invention makes it possible to apply white or colored light in the information-wise exposure.

By using organic spectral sensitizing agents, e.g. that are within the scope of the definition of class (B) and that have in their structure a conjugated system of sufficient length, it is possible to extend the spectral sensitivity into the visible light spectrum and even into the infrared.

The photosensitive inorganic compounds applied in the present invention as sensitizing agent for the photochemical formation of the dyestuff salts may itself in a known way be sensitized spectrally by dyes useful for that purpose. So, when photoconductive zinc oxide is used it may be treated with the different types of spectral sensitizing agents known for it form its application in electrophotography. Preferred spectral sensitizing dyes for the photosensitive composition used in the present invention belong to the class of the internally ionized dyes, e.g. merocyanines and the styryl and styryl vinyl dye bases as described, e.g. in Photographic Chemistry vol. II by P. Glafkides. Fountain PressLondon (1960), pp. 844-845 and in the French patent specification 1,574,740 filed Mar. 11, 1968 by Bell & Howell.

The spectral sensitization over the whole visible spectrum opens the possibility to produce print-out multicolor prints by means of one and same recording material. So, on using a recording material containing superposed recording layers sensitized respectively in the red, green, and blue region of the spectrum and containing the proper dye forming combination superposed cyan, magenta and yellow part images can be produced that offer a full reproduction of the multicolor original used in the information-wise exposure.

The recording materials sensitized according to the present invention are suited to produce print-out images of different color according to the type of spiropyran compound applied.

The stabilization of the obtained prints may proceed by washing out the residual free radical generator with a suitable solvent or solvent mixture, e.g. a hydrocarbon liquid such as petroleum ether optionally mixed with acetone, or by simply evaporating it by raising the temperature when the compound involved is sufiiciently volatile. For the latter purpose and the high photosensitivity, carbon tetrabromide or a mixture of carbon tetrabromide and iodoform is preferred.

According to a preferred recording and reproduction process of the present invention the information-wise exposure is carried out in such a way that first a latent image is produced which is transformed into a visible dye image by means of a so-called optical development.

The optical development proceeds by exposing the recording layer containing the latent or barely visible image over its entire surface with visible radiation which lies in the spectral absorption band of the products formed by the image-wise exposure and image-wise interaction of the photoexposed ingredients 1) and (2) of the mentioned photosensitive composition. In the overall exposure no exposure light is applied to which the photosensitive polyhalogen compound is inherently sensitive since thereby the effect of the image-wise exposure is masked by an overall coloration. It is advantageous to use in the optical development exposure a cut-off filter absorbing all the light corresponding with the wavelength range that is inherently absorbed by the ingredients of the non-previously exposed recording layer.

The optical development effect is markedly speeded up and the image density increased by applying heat, e.g. supplied by contact with a hot body or through infrared radiation during the overall exposure to visible light.

The increase of speed of the optical development is very outspoken by the use of poly-N-vinyl carbazole and the copolymers containing N-vinyl carbazole units.

The optical development speed obtains a particularly high value by the use of poly-N-vinyl carbazole or the copolymers containing N-vinyl carbazole units in combination with the mercapto compounds of Class D. The addition of a triarylstibine such as triphenylstibine to that combination intensifies the image density obtained by the optical development procedure.

It is assumed that during the exposure applied in the optical development at least a part of the overall applied light energy is visible light, absorbed by a dyestuff salt having the pyrylium structure when using a diarylo spiropyran or having an indolinium salt structure when using an indolino-arylospiropyran. Said salt seems to act as a spectral sensitizing agent for a chemical reaction between the photosensitive polyhalogen compound producing the necessary radicals for forming the dyestufi salt with the spiropyran.

In a particular preferred composition for forming print out as well as optical developable prints a mixture of CBr and CHJ yielding a superadditive sensitivity effect is used.

Preferred recording layer compositions contain a spiropyran compound or mixture of spiropyran compounds and poly-N-vinylcarbazole in a ratio by weight within the range of :100 to 10: and a photosensitive polyhalogen compound such as carbon tetrabromide or iodoform or a mixture of both said polyhalogen compounds with respect to poly-N-vinylcarbazole in a ratio by weight in the range of 100 to 20:100. In such compositions photoconductive zinc oxide is preferably used in a ratio by weight of 1:4 with respect to the poly-N-vinyl carbazole.

Said recording layer compositions comprise preferably an anti-fogging agent e.g. triphenyl stibine or 2,6-di-tert. butyl-p-cresol.

Preferred amounts of anti-fogging agent such as said p-cresol are with respect to photosensitive carbon tetrabromide and/or iodoform within the weight ratio range of 10:100 to 2.5:100.

According to an alternative embodiment of the optical development technique the recording material is first overall exposed to electromagnetic radiation to produce nondilferentially over the whole recording layer latent dyestuif centers that are afterwards optically developed information-wise by a sufficiently strong information-wise exposure in the absorption band of the dyestufl centers. Optionally the information-wise exposure proceeds simultaneously with an overall heating, e.g. effected by an overall infra-red light exposure.

Instead of applying an overall pre-exposure to form the dyestulf centers these dyestuffs may be added, e.g. applied by imbibition (diffusion) in minor amounts to the recording layer composition to act as optical development nuclei for the dye image formation by image-wise exposure.

According to a special embodiment the spiropyrans are formed in the nonexposed recording layer composition in situ by starting from the corresponding pyrylium and indolinium salts and adapting the pH in a proper way to obtain the spiropyrans that may be considered as the dyestuif precursors of the pyrylium and indolinium salts, respectively.

The information-wise exposure applied in the present invention may be a contact exposure of the direct or retflex type and also an optical projection exposure as applied, e.g. in an optical enlarging apparatus. The information-wise exposure need not be simultaneous in all parts of the recording material. The exposure may be progressive in one continuous step as, e.g. in sound track recording or in successive intermittent steps provided that the required information-wise change is obtained. Thus the recording material may be scanned with an image-wise modulated radiant energy spot of high intensity, e.g. a laser beam, or the material may be progressively exposed through a slit, e.g. is exposed to copying light of a tubular lamp that is given a translation movement along the original.

A recording material of the present invention being suited for the recording of information in the form of modulated ultraviolet radiation can be used in X-ray and electron-beam recording. X-ray beams can be absorbed in high energy absorbing substances and create by means of them so-called secondary photons, e.g. of the ultraviolet radiation energy band and photoelectrons that are absorbed by the photosensitive polyhalogen compound forming through its photoradicals a dyestulf salt with the spiropyran. Substances for high energy absorption that may be incorporated in the recording element contain the elements lead, mercury, bismuth, barium and/ or tungsten. Lead compounds that themselves are photosensitive are preferred, e.g. lead monoxide, lead bromide and lead iodide.

Suitable light sources for use in a recording method of the present invention are ultraviolet light sources, xenongas lamps, incandescent bulbs, the light of the sun and flash lamps. In the overall exposure for the optical development an infrared lamp emitting also in the visible spectrum is preferably used.

Electron beam and laser beam recording proceed with the apparatus suited for that purpose and known to those skilled in the art.

Recording materials of the present invention are very versatile in that they by the use of a proper sensitizing agent can be applied for continuous tone or halftone reproduction. They can offer very contrasty images so that they are very suited for the reproduction of line and screen type originals and find a successful use in a great variety of graphic art applications.

The reflex-exposure properties of the present recording materials make them very useful in the document reproduction sector since they offer in a reflex-contact exposure print-out images of a sufiiciently intense spectral density.

According to a special application a recording layer as described herein is used in conjunction with a magnetic recording layer and is more particularly applied at the rear side of a flexible tape support carrying the magnetic recording layer. Using such a material a sound track is formed in the magnetic recording layer and a visual text image corresponding with the sound track photographed on the recording layer of the present invention.

Such a recording material thus allows the storing of optical and acoustic signals and makes it possible to reproduce both informations simultaneously.

The present invention is illustrated by the following examples, without, however, limiting it thereto. The percentages are by weight unless otherwise indicated.

EXAMPLE 1 An intimate mixture of 500 mg. of carbon tetrabromide, mg. of di-fi-naphthospiropyran, 100 mg. of photoconductive zinc oxide (average grain size 10 micron) and 500 mg. of polystyrene dissolved in 8 ml. of methylene chloride was coated at a thickness of 0.1 mm. onto an unsubbed polyethylene terephthalate film. The coated layer was dried at 50 C.

An image-wise 2 sec. contact-exposure through a halftone transparency with a high pressure mercury vapor lamp placed at a distance of 10 cm. and sold by Philips Gloeilampenfabrieken N.V., the Netherlands as HPL lamp-80 w. (trade name) yielded a latent image.

The latent image was optically developed by an overall exposure by means of an infrared lamp of 250 w. (sold by Bie and Bernsten, 35 Pilestraede, Copenhagen, Denmark) emitting also in the visible part of the spectrum. Between the infrared lamp and the recording layer a cutoff filter was placed absorbing all the light with a wavelength smaller than 580 nm. (Corning C.S. 3-63).

Within an overall exposure period of 3 min. a visible image having a purple color tone and having opposite image values With respect to the original was obtained. The obtained image was stabilized by heating at 120 C.

In the absence of photoconductive zinc oxide the same optical development result could only be obtained by applying for forming the latent image an image-wise exposure lasting 2 min.

EXAMPLE 2 An intimate mixture of 250 mg. of carbon tetrabromide,

250 mg. of iodoform, 25 mg. of di-p-naphthospiropyran, 30 mg. of 2,6-ditert. butyl-p-cresol and 100 mg. of photoconductive zinc oxide prepared by oxidation of zinc vapor (average grain size 10 micron) and 8 ml. of a 5% solution of polystyrene in methylene chloride was coated at a thickness of 0.1 mm. onto an unsubbed polyethylene terephthalate film.

After drying in the dark the recording layer was exposed for 2 min. through a grey wedge (constant 0.15) with an ultra-violet light-emitting lamp type HPL- w. (trade name) placed at a distance of 10 cm. The exposure resulted in the print-out of 8-9 steps.

An image-wise exposure of less than 1 see. with the same ultraviolet light emitting lamp placed at the same distance ofiered already a weak print-out image, which was optically developed to yield an optical dense image by means of an overall exposure lasting 60 sec. carried out with a 250 w. infrared lamp using a cut-off filter absorbing all the light having a wavelength smaller than 580 nm.

The image was stabilized at C. and was free from background coloration.

EXAMPLE 3 A same photosensitive recording layer as discribed in Example 2 was prepared, but the 2,6-di-tert.butyl-p-cresol was left out of the composition.

A same print-out exposure as described in Example 2 yielded the reproduction of 10 visible steps with a higher spectral density.

The optical development of a hardly visible image obtained in an image-wise exposure of less than 1 see. with the same HPL 80 w. (trade name) ultraviolet lamp yielded after a 20 sec. infrared exposure under the same conditions as described in Example 2 a visible image with a maximum optical density larger than 1.

A thermal image stabilization was carried out at 120 C. and resulted in a cyan image with faint image background coloration.

EXAMPLE 4 A same photosensitive recording layer as described in Example 2 but containing in addition 5 mg. of a merocyanine dye having the following structure:

was prepared.

The obtained recording layer was image-wise contactexposed for 2 sec. in a 3M 179 (trade name) Contact Printer Processor using a light source emitting visible light.

The obtained latent image was optically developed by means of an overall exposure lasting 2 min. and effected by a 250 w. infrared lamp emitting through a cut-off filter absorbing all the light below 580 nm.

The visible image had an optical density of more than 1.

EXAMPLE 5 An intimate mixture of 300 mg. of carbon tetrabromide, mg. of iodoform, 30 mg. of di-B-naphthospiropyran,

30 mg. of 2,6-di-tert.butyl-p-cresol, 50 mg. of photoconductive zinc oxide (average grain size 10 micron) and 8 ml. of a 5% solution of poly-N-vinylcarbazole in methylene chloride was coated at a thickness of 0.1 mm. onto an unsubbed polyethylene terephthalate film. Drying of the coating proceeded at 50 C.

The recording layer was image-wise contact-exposed for 0.5 sec. through a halftone transparency with an ultraviolet lamp type HPL-80 w. (trade name) placed at a distance of 10 cm.

A hardly visible image was obtained the density of which was increased by optical development proceeding with an overall exposure lasting 2 sec. and being carried out by means of an infrared lamp of 250 w. placed at a distance of 15 cm. Between the recording layer and the infra-red lamp a cut-off filter absorbing all the light below 540 nm. was placed.

The obtained visible image was stabilized by a rinsing treatment in butyl acetate.

EXAMPLE 6 A photosensitive composition consisting of 0.5 g. of carbon tetrabromide, 0.1 g. of yellow photoconductive lead(II)monoxide, 0.01 g. of di-fl-naphthospiropyran, and 8 ml. of a solution of polystyrene in methylene chloride was coated at a thickness of 0.10 mm. onto a nonsubbed polyethylene terephthalate support. The coating was dried at 50 C.

In order to obtain a latent image the recording material was contact-exposed in a vacuum frame for see. through a halftone transparency using a Chemco (trade name of Chemcut Corp.) exposure apparatus Model D-7 Double Sided Photoprinter containing 9 UV-fluorescent lamps of each w.

The latent image was optically developed by means of an overall exposure lasting 3 min. and elfected by means of a 250 w. infrared lamp placed at a distance of 15 cm. Between the infrared lamp and recording material a cutotf'filter (Corning CS 3-67) was placed absorbing all the light with a wavelength smaller than 540 nm.

The obtained cyan image having a density of 1.5 was stabilized by heating the recording material for several minutes at 120 C.

A same recording material but not containing the lead (II) monoxide needed an image-wise exposure of 2 min. and optical development exposure of 3 min. in order to yield the same image result as described above.

We claim:

1. A photographic process for forming a visible image in a recording material which comprises in intimate admixture:

( 1) at least one spiropyran compound of the group consisting of a spirodibenzopyran, a spirodinaphthopyran, a spirobenzonaphthopyran, a 1,3,3-trimethylindolino-benzospiropyran, a 1,3,3-trimethylindolinonaphthospiropyran, or a spiropyran that contains a condensed anthracene or phenanthrene nucleus;

(2) at least one ultra-violet light-sensitive organic polyhalogen compound capable of producing on exposure with ultraviolet light a dye salt with the spiropyran compound and having the general formula:

A x B Y wherein:

each of A, B, X and Y is a chlorine, bromine or iodine atom; or one of said radicals A, B, X or Y is an alkyl group, an aryl group, or an aroyl group and the other radicals are each chlorine, bromine or iodine; or two of said radicals A, B, X or Y each is an aromatic acyl group and the other radicals are each chlorine, bromine or iodine; and

(3) in working relationship with said mixture photoconductive zinc oxide or photoconductive lead(II) monoxide, said process comprising the steps of exposing said recording material to activating electromagnetic radiation of an intensity sufficient to produce a visible image directly or a latent image that can be rendered visible by optical development.

2. The process of claim 1 wherein said exposure produces a latent image and said latent image is optically developed and comprising the steps of: imagewise exposing the recording material to activating electromagnetic radiation of an intensity sufiicient to bring about a latent or barely visible image having an increased spectral sensitivity in a wavelength range outside the inherent sensitivity range of the ultraviolet light-sensitive compound, and then uniformly exposing the entire imagewise exposed recording material to light within the wavelength range for which the initially exposed portions are of increased sensitivity than the initially non-exposed portions, thereby increasing the visibility of said initially formed image.

3. The process of claim 1 wherein said exposure produces a latent image and said latent image is optically developed and comprising the steps of: uniformly exposing the entire recording material to electromagnetic radiation of an intensity sufiicient to bring about in the recording material an increase in its spectral sensitivity in a wavelength range outside the inherent sensitivity range of the ultraviolet light-sensitive compound, and then imagewise exposing the overall exposed recording material within the wavelength range for which the overall exposed recording material is of increased sensitivity to increase the visibility of the initially formed image.

4. A photographic process according to claim 1 wherein the recording material after the formation of a visible image is overall heated to bring about image stabilization.

5. A photographic process according to claim 1 wherein said spiropyran compound corresponds to one of the following general formulae:

wherein:

R, R R',, R R' R and R' each represent hydrogen, alkyl, alkyl substituted with halogen, alkyl substituted with an ester group, alkyl substituted with a carboxyl group, alkyl substituted with a N-phenylcarbamyl group, a hydroxy group, an alkoxy group, an aryloxy group, a phenyl group, piperidyl, acetyl,

halogen, nitro, or R and R, together represent a --(CH chain wherein n=2 or 3 to link the carbon atoms in the 3 and 3' positions together.

6. A process according to claim 1 wherein said ultraviolet light-sensitive compound is carbon tetrabromide or iodoform.

7. A process according to claim 1 wherein said ultraviolet light-sensitive compound is a mixture of carbon tetrabromide and iodoform is used.

8. A process according to claim 1 wherein said mixture is used in association with at least one sensitizing compound having one of the following structural formulae:

wherein:

n is a positive integer of at least 2, and

R is hydrogen or an alkyl group.

9. A process according to claim 1 wherein said recording material contains as an antifogging agent a triaryl compound of a group V element or a sterically hindered phenol.

10. A process according to claim 1 wherein the mixture is present in a layer of at least one polymeric binding agent of the group of styrene, vinyl acetate, acrylonitrile, acrylic acid ester, methacrylic acid ester, N-vinylcarbazole or butadiene units, a hydrophobic cellulose derivative, a phenoxy resin or polyester polycondensate.

11. A process according to claim 1 wherein the exposure is a direct exposure.

12. A process according to claim 1 wherein the exposure is a reflux exposure.

13. A process according to claim 1 wherein the exposure is an electron beam exposure.

14. A photosensitive recording material for the direct production of a visible image by imagewise exposure to activating electromagnetic radiation which comprises a layer of an intimate mixture consisting essentially of:

(1) at least one spiropyran compound of the group consisting of a spirodibenzopyran, a spirodinaphthopyran, a spirobenzonaphthopyran, a 1,3,3-trimethylindolino benzospiropyran, a 1,3,3 trimethylindolinonaphthospiropyran, or a spiropyran that contains a condensed anthracene or phenanthrene nucleus; (2) at least one ultraviolet light-sensitive organic polyhalogen compound capable of producing on exposure with ultraviolet light a dye salt with the spiropyran compound and having the general formula:

wherein:

each of A, B, X and Y is a chlorine, bromine or iodine atom; or one of said radicals A, B, X or Y is an alkyl group, an aryl group, or an aroyl group and the other radicals are each chlorine, bromide or iodine; or two of said radicals A, B, X or Y each is an aromatic acyl group and the other radicals are each chlorine, bromine or iodine; and

(3) in working relationship with said mixture photoconductive zinc oxide or photoconductive lead(II) monoxide.

30 15. A photographic material according to claim 14 wherein said spiropyran compound corresponds to one of the following general formulae:

N an,

R1 R'r R,

wherein:

R, R R',, R R'g, R and R; each represent hydrogen, alkyl, alkyl substituted with halogen, alkyl substituted with an ester group, alkyl substituted with a carboxyl group, alkyl substituted with a N-phenylcar- 'bamyl group, a hydroxy group, an alkoxy group, an aryloxy group, a phenyl group, piperidyl, acetyl, halo- =gen, nitro, or R and R; together represent a --(CH chain wherein n=2 or 3 to link the carbon atoms in the 3 and 3' positions together.

16. A material according to claim 14 wherein said ultraviolet light-sensitive compound is carbon tetrabromide or iodoform.

17. A material according to claim 14 wherein said ultraviolet light-sensitive compound is a mixture of carbon tetrabromide and iodoform is used.

18. A material according to claim 14 wherein said mixture is used in association with at least one sensitizing compound having one of the following structural formulae:

N CH:

CH: t

c-o l/ H.

wherein:

n is a positive integer of at least 2, and

R is hydrogen or and alkyl group.

19. A photosensitive recording material according to claim 14, containing as an antifogging agent a triaryl compound of a group V element and a sterically hindered phenol.

20. A photosensitive recording material according to claim 14, wherein the recording material contains said spiropyran compound in admixture with said photosensitive organic polyhalogen compound in a ratio by weight of 1:1-50.

21. A photosensitive recording material according to claim 20 wherein the recording material contains triphenyl stilbine with respect to said photosensitive polyhalogen compound in a ratio by weight in the range of 1:100 to 2.5:100.

32 References Cited UNITED STATES PATENTS 3,147,117 9/1-964 Wainer, et a1 96-48 3,667,949 6/1972 Inoue, et a1. 96-48 3,642,479 2/1972 Van Allan, et a1. 96--90 PC X 3,486,899 12/ 1969 Brown 96-90 PC 3,660,086 5/1972 Tamai et a1. 96-90 PC X 3,359,105 12/ 1967 Wainer 96-90 X 3,558,317 1/ 1971 Petro et a1. 96-90 3,322,542 5/1967 Ullman et a1. 9690 PC 3,436,353 4/1969 Dreyer et al. 96--90 PC X 3,510,300 5/ 1970 Fotland et al 96-90 X 3,620,742 11/1971 Willems et a1 9615 R FOREIGN PATENTS 1,274,655 8/1968 Germany 96-90 PC RONALD H. SMITH, Primary Examiner W. H. LOUIE, JR., Assistant Examiner US. Cl. X.R.

96-90 PC, 48 QP, 90 R, 88, 1.5, 1.8; 250-323 

